1. Field of the Invention
This invention relates to thread handling and feeding mechanisms for sewing machines and more particularly to an improved mechanism for feeding and controlling the threads employed in an overedge sewing machine of the type employed to form an overedge seam along the edge of a workpiece.
2. Description of the Prior Art
Overedge sewing machines of the type illustrated in copending U.S. Patent application Ser. No. 354,714, now U.S. Pat. No. 3,881,434, assigned to the assignee of the present invention, are commonly employed to form a seal with two or three threads. When two or three threads are employed for the seam, the problems of handling the threads, including controlling the feeding, tension, and timing of the takeup to draw the stitches tight, are greatly complicated as each thread must be controlled relative to the other threads in order to properly form a standard stitch seam.
Numerous threading arrangements have been developed in the past for controlling and feeding the threads of an overedge sewing machine, one example being illustrated in U.S. Pat. No. 2,949,901. However, these prior art thread control machines have generally not been readily adaptable to other machines. Further, many of them have not been easily threaded, requiring extensive down time for rethreading when a thread is broken, due to the relatively inaccessible location of portions of the thread control mechanism. Also, many of the prior art devices have been difficult to adjust to maintain proper control and tension in the threads.